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Avian-Style Growth in Dinosaurs from Lourinhã.



This just in...

  de Ricqles, A.; Mateus, O.; Antunes, M. Telles ; & Taquet, P.
2001. Histomorphogenesis of embryos of Upper Jurassic Theropods
from Lourinhã (Portugal). _Comptes rendus de l'Académie des
sciences - Série IIa - Sciences de la Terre et des planètes_
332(10): 647-656.

  Avian-style bone formation occurs in two dinosaurian embryos
and other immature specimens from Lourinhã, Portugal.

  The abstract reads:

  "Remains of dinosaurian embryos, hatchlings and early
juveniles are currently the subject of increasing interest, as
new discoveries and techniques now allow to analyse
palaeobiological subjects such as growth and life history
strategies of dinosaurs. So far, available `embryonic' material
mainly involved Ornithopods and some Theropods of Upper
Cretaceous age. We describe here the histology of several bones
(vertebrae, limb bones) from the tiny but exceptionally well
preserved in ovo remains of Upper Jurassic Theropod dinosaurs
from the Paimogo locality near Lourinhã (Portugal). This
Jurassic material allows to extend in time and to considerably
supplement in great details our knowledge of early phases of
growth in diameter and in length of endoskeletal bones of
various shape, as well as shape modelling among carnivorous
dinosaurs. Endochondral ossification in both short and long
bones involves extensive pads of calcified cartilages permeated
by marrow buds. We discuss the likely occurrence of genuine
cartilage canals in dinosaurs and of an avian-like `medullary
cartilaginous cone' in Theropods. Patterns of periosteal
ossification suggest high initial growth rates (20 µ m·day-1 or
more), at once modulated by precise and locally specific changes
in rates of new bone deposition. The resulting very precise
shape modelling appears to start early and to involve at once
some biomechanical components."

  And before anyone asks, I do not have further access to this
paper, as of yet...

=====
Jaime A. Headden

  Aaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhr-gen-ti-na
  Where the Wind Comes Sweeping Down the Pampas!!!!

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